Transcription factors NF-κB and AP-1 are involved in regulating the expression of a number of genes involved in mediating inflammatory and immune responses. NF-κB regulates the transcription of genes including TNF-α, IL-1, IL-2, IL-6, adhesion molecules (such as E-selectin) and chemokines (such as Rantes), among others. AP-1 regulates the production of the cytokines TNF-α, IL-1, IL-2, as well as, matrix metalloproteases. Drug therapies targeting TNF-α, a gene whose expression is regulated by both NF-κB and AP-1, have been shown to be highly efficacious in several inflammatory human diseases including rheumatoid arthritis and Crohn's disease. Accordingly, NF-κB and AP-1 play key roles in the initiation and perpetuation of inflammatory and immunological disorders. See Baldwin, A. S., Journal of Clin. Investigation, 107:3 (2001); Firestein, G. S. et al., Arthritis and Rheumatism, 42:609 (1999); and Peltz, G., Curr. Opin. in Biotech., 8:467 (1997).
There are many signaling molecules (kinases and phosphatases) upstream of AP-1 and NF-κB which are potential therapeutic drug targets. The kinase JNK plays an essential role in regulating the phosphorylation and subsequent activation of c-jun, one of the subunits which constitute the AP-1 complex (fos/c-jun). Compounds which inhibit JNK have been shown to be efficacious in animal models of inflammatory disease. See Manning, A. M. et al., Nature Rev. Drug Disc., 2:554 (2003). A kinase critical to the activation of NF-κB is the IκB kinase (IKK). This kinase plays a key role in the phosphorylation of IκB. Once IκB is phosphorylated it undergoes degradation leading to the release of NF-κB which can translocate into the nucleus and activate the transcription of the genes described above. An inhibitor of IKK has been shown to be efficacious in animal models of inflammatory disease. See Burke, J. R., Curr. Opin. Drug Discov. Devel., 6(5):720-728 (September 2003).
In addition to inhibiting signaling cascades involved in the activation of NF-κB and AP-1, the glucocorticoid receptor has been shown to inhibit the activity of NF-κB and AP-1 via direct physical interactions. The glucocorticoid receptor (GR) is a member of the nuclear hormone receptor family of transcription factors, and a member of the steroid hormone family of transcription factors. Affinity labeling of the glucocorticoid receptor protein allowed the production of antibodies against the receptor which facilitated cloning the glucocorticoid receptors. For results in humans see Weinberger et al., Science, 228:740-742 (1985); Weinberger et al., Nature, 318:670-672 (1986) and for results in rats see Miesfeld, R., Nature, 312:779-781 (1985).
Glucocorticoids which interact with GR have been used for over 50 years to treat inflammatory diseases. It has been clearly shown that glucocorticoids exert their anti-inflammatory activity via the inhibition by GR of the transcription factors NF-κB and AP-1. This inhibition is termed transrepression. It has been shown that the primary mechanism for inhibition of these transcription factors by GR is via a direct physical interaction. This interaction alters the transcription factor complex and inhibits the ability of NF-κB and AP-1 to stimulate transcription. See Jonat, C. et al., Cell, 62:1189 (1990); Yang-Yen, H. F. et al., Cell, 62:1205 (1990); Diamond, M. I. et al., Science, 249:1266 (1990); and Caldenhoven, E. et al., Mol. Endocrinol., 9:401 (1995). Other mechanisms such as sequestration of co-activators by GR have also been proposed. See Kamei, Y. et al., Cell, 85:403 (1996); and Chakravarti, D. et al., Nature, 383:99 (1996).
In addition to causing transrepression, the interaction of a glucocorticoid with GR can cause GR to induce transcription of certain genes. This induction of transcription is termed transactivation. Transactivation requires dimerization of GR and binding to a glucocorticoid response element (GRE).
Recent studies using a transgenic GR dimerization defective mouse which cannot bind DNA have shown that the transactivation (DNA binding) activities of GR could be separated from the transrepressive (non-DNA binding) effect of GR.
These studies also indicate that many of the side effects of glucocorticoid therapy are due to the ability of GR to induce transcription of various genes involved in metabolism, whereas, transrepression, which does not require DNA binding leads to suppression of inflammation. See Reichardt, H. M. et al., Cell, 93:531 (1998) and Reichardt, H. M., EMBO J., 20:7168 (2001).
Compounds that modulate AP-1 and NF-κB activity would be useful in the treatment of inflammatory and immune diseases and disorders such as osteoarthritis, rheumatoid arthritis, multiple sclerosis, asthma, inflammatory bowel disease, transplant rejection and graft vs. host disease.
Also, with respect to the glucocorticoid receptor pathway, it is known that glucocorticoids are potent anti-inflammatory agents, however their systemic use is limited by side effects. Compounds that retain the anti-inflammatory efficacy of glucocorticoids while minimizing the side effects such as diabetes, osteoporosis and glaucoma would be of great benefit to a very large number of patients with inflammatory diseases.
Additionally concerning GR, the art is in need of compounds that antagonize transactivation. Such compounds may be useful in treating metabolic diseases associated with increased levels of glucocorticoid, such as diabetes, osteoporosis and glaucoma.
Additionally concerning GR, the art is in need of compounds that cause transactivation. Such compounds may be useful in treating metabolic diseases associated with a deficiency in glucocorticoid. Such diseases include Addison's disease.